Calculations of the magnetic entropy change $\Delta S_{\mathrm{mag}}$ and the magnetocaloric effect (i.e., the adiabatic temperature change) $\Delta T_{\mathrm{ad}}$ in ${\mathrm{DyAl}}_2,{\mathrm{ErAl}}_2,$ and ${\mathrm{DyNi}}_2$ using a Hamiltonian that takes into account the effects of crystalline electrical field and exchange interaction have been carried out. Good agreement between the theory and the experiment was obtained using the crystal-field parameters from inelastic neutron scattering for ${\mathrm{DyAl}}_2$ and ${\mathrm{ErAl}}_2.$ The crystal-field parameters for ${\mathrm{DyNi}}_2,$ which were reported from magnetization measurements, did not give good agreement between the theory and the experiment. Using the experimental $\Delta S_{\mathrm{mag}}$ versus T, and $C_{\mathrm{mag}}$ versus T (where $C_{\mathrm{mag}}$ is the magnetic heat capacity) we made an estimate of the crystal-field parameters for ${\mathrm{DyNi}}_2,$ which yield a satisfactory agreement between the theory and the experiment with regard to $\Delta S_{\mathrm{mag}}$ and $\Delta T_{\mathrm{ad}}.$ The appearance of a hump in the theoretical $\Delta S_{\mathrm{mag}}\mathrm{}\left(T\right)\mathrm{}$ below the Curie temperature is discussed.

• Received 17 March 1998

DOI:https://doi.org/10.1103/PhysRevB.58.12110